When I was down in June, our 1:10pm flight ended up being 15 minutes late. That plus the fact baggage has been really slow lately got us to the dock at 2:!0. They wouldn't let us on and the ferry actually left the dock 5 minutes early. As the 5 pm ferry is a different company, you can't exchange tickets, luckily I pay the insurance and after much "conversation" We ended up having to pay and extra $20 per ticket for the 5pm ferry on the other ferry company. I went down three weeks ago and again our flight to St Thomas looked to make the 2:30 ferry doable, we bought tickets for the 5 pm ferry and enjoyed a couple drinks upstairs. When we went to the check-in counter to get our prepaid tickets, There was a guy being denied on 2:30 as it was 20 minutes before leaving. They said it was too late. Hopefully when the new season starts they will allow more ferries, until then I'm playing it safe.
I do remember pre-covid days even if we were running close, a call from Kevin (our taxi guy) and the ferry would wait for us. For now, I'd take the 5pm ferry and reduce the stress of getting to Roadtown.